Laminated sheet material



Nov. 21, 1933. c. E. BEECHER 1,936,375

LAMINATED SHEET MATERIAL Filed Dec. 18, 1929 Patented Nov. 21, 1933 UNITED STATES PATENT OFFICE 1,936,375 LAMINATED SHEET MATERIAL Application December 18, 1929 Serial No. 414,864

1 Claim. (Cl. 154-50) This invention relates to a laminated sheet material and method of making the same and has particular reference to a laminated paper.

In providing containers for such materials as 5 potato chips or the like, which contain a considerable amount of grease, it is customary to use transparent bags through which the contents may be viewed. Heretofore such transparent bags have been generally made of paper having a capacity for resisting grease to a more or less limited degree. However, the paper heretofore used for such purpose is not effectively greaseproof, with the result that it does not prevent the penetration of grease which, on contact with the air, tends to become rancid, to the detriment of the contents. Furthermore, it is customary to print, upon the exterior of such bags, the maker's name and advertising matter, which printing is destroyed or rendered ineffective by the penetratmg grease.

It is the object of the present invention to provide a sheet material which will be transparent and at the same time grease and moisture proof to a high degree and which will obviate the ob- 2'5 jections indicated above in connection with containers for greasy products. It is also an object of the invention to provide an improved method of making such material.

In the accompanying drawing, the figure discloses a diagrammatic cross section of the improved sheet. material.

The improved sheet material consists of sheets 2 and 4 which are formed in a known manner by sheeting pure thoroughly hydrated pulp, preferably sulphite pulp of spruce, producing a greaseproof paper, then wetting this sheeted product, and supercalendering by ironing out the wetted sheet by the application of heat and pressure. The material thus produced is grease-proof and 40 also non-absorbent of wear. It is of fine texture and transparent and may be printed upon in the same fashion as ordinary paper. The two sheets 2 and 4 formed in this manner are adhered togather by a film of parafline 6 which, by reason of the fact that the sheets are substantially nonabsorbent of either paraiilne or other wax, is substantially confined to the inner faces of the sheets.

The parafllne is entirely absent from the outer faces of the laminated material.

when the two sheets are thus Joined by an intermediate film or layer of par-affine, the resultant material is of a high degree of transparency.

This transparency is greater than that ordinarily 5 obtained by impregnating ordinary 9 9 with 5 wax.

to use other mineral,

The resultant material is not only grease, air and moisture proof, but also substantially waterproof. The fact that it is moisture-proof and substantially water-proof is due to the presence of the intermediate film of wax, through which the moisture cannot penetrate even though it may penetrate the outersheets. On the other hand, the material is grease-proof because the outer sheets are of the grease-proof paper formed in the manner described. These outer 55 sheets also prevent contact between the contents of a bag or package made of the material, so as to avoid imparting the taste of wax thereto as would occur with use of ordinary waxed paper. Inasmuch as the wax does not penetrate the outer layers of the material, the material ,may be readily formed into bags on the ordinary bag machine, or formed into other desired type of container, and may be readily and permanently printed upon.

The preferred method of forming 'the material comprises continuously coating the surface of one moving sheet with molten parafllne wax, thereafter applying a second similar sheet to the waxed surface of the first sheet, the composite material being then compressed between rollers with the application of heat so as to firmly adhere the two sheets together with an intermediate very thin film of wax.

While the preferred material is made specifically as described above, it will be understood that material having very similar properties may be made using pulps of other types whereby cheaper grades of the material may be formed. The grease-proof and transparent feature of the paper is secured by thoroughly hydrating pulp, then sheeting and thereafter moistening and ironing out the sheets with the application of heat and pressure. Instead of using paraiflne wax to form the intermediate film, it is possible animal or vegetable waxes which in general are not absorbed by the exterior sheets of this paper.

What I claim and desire to protect by Letters Patent is:

A transparent, grease and moisture proof laminated sheet material consisting of supercalendered sheets of greaseproof paper ioinedby an intermediate film of wax substantially confined to the inner faces of the sheets.

CHESTER E. BEECHER. 

